This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of the studies in this project is to obtain in vivo confirmation of the potential antiparkinsonian effects of blockade of NR2D-type NMDA receptors in an animal model of Parkinson's disease, the 6-OH-dopamine-lesioned rat. These agents are most likely to work by blocking NR2D receptors in the subthalamic nucleus, a structure which is overactive in Parkinson's disease. NR2D receptor blockade may act to normalize the activity in this nucleus. To test this hypothesis, three experiments are planned: (1) We will establish the concentration-effect curve for inhibition of native NR2D-containing NMDA receptors in subthalamic neurons by our best NR2D-selective antagonist. The combination of these data with in vivo pharmacokinetic data will allow us to estimate receptor occupancy as a function of administered dose. (2) We will determine the NR2D protein distribution using immunohistochemistry in normal rats and rats treated with 6-OH-dopamine to confirm that NR2D receptors are present in this animal model of Parkinson's disease. (3) We will evaluate the ability of selective blockade of NR2D-containing receptors in basal ganglia neurons to alter motor behavior in 6-OHDA-lesioned animals.